1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 // Details of the algorithm:
12 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
14 //===----------------------------------------------------------------------===//
16 #define DEBUG_TYPE "asan"
18 #include "llvm/Transforms/Instrumentation.h"
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/DepthFirstIterator.h"
22 #include "llvm/ADT/OwningPtr.h"
23 #include "llvm/ADT/SmallSet.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/DIBuilder.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/Function.h"
31 #include "llvm/IR/IRBuilder.h"
32 #include "llvm/IR/InlineAsm.h"
33 #include "llvm/IR/IntrinsicInst.h"
34 #include "llvm/IR/LLVMContext.h"
35 #include "llvm/IR/Module.h"
36 #include "llvm/IR/Type.h"
37 #include "llvm/InstVisitor.h"
38 #include "llvm/Support/CommandLine.h"
39 #include "llvm/Support/DataTypes.h"
40 #include "llvm/Support/Debug.h"
41 #include "llvm/Support/raw_ostream.h"
42 #include "llvm/Support/system_error.h"
43 #include "llvm/Target/TargetMachine.h"
44 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
45 #include "llvm/Transforms/Utils/BlackList.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Transforms/Utils/ModuleUtils.h"
53 static const uint64_t kDefaultShadowScale = 3;
54 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
55 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
56 static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G.
57 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
59 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
60 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
61 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
63 static const char *kAsanModuleCtorName = "asan.module_ctor";
64 static const char *kAsanModuleDtorName = "asan.module_dtor";
65 static const int kAsanCtorAndCtorPriority = 1;
66 static const char *kAsanReportErrorTemplate = "__asan_report_";
67 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
68 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
69 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
70 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
71 static const char *kAsanInitName = "__asan_init_v1";
72 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
73 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
74 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
75 static const char *kAsanStackMallocName = "__asan_stack_malloc";
76 static const char *kAsanStackFreeName = "__asan_stack_free";
77 static const char *kAsanGenPrefix = "__asan_gen_";
78 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
79 static const char *kAsanUnpoisonStackMemoryName =
80 "__asan_unpoison_stack_memory";
82 static const int kAsanStackLeftRedzoneMagic = 0xf1;
83 static const int kAsanStackMidRedzoneMagic = 0xf2;
84 static const int kAsanStackRightRedzoneMagic = 0xf3;
85 static const int kAsanStackPartialRedzoneMagic = 0xf4;
87 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
88 static const size_t kNumberOfAccessSizes = 5;
90 // Command-line flags.
92 // This flag may need to be replaced with -f[no-]asan-reads.
93 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
94 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
95 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
96 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
97 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
98 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
99 cl::Hidden, cl::init(true));
100 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
101 cl::desc("use instrumentation with slow path for all accesses"),
102 cl::Hidden, cl::init(false));
103 // This flag limits the number of instructions to be instrumented
104 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
105 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
107 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
109 cl::desc("maximal number of instructions to instrument in any given BB"),
111 // This flag may need to be replaced with -f[no]asan-stack.
112 static cl::opt<bool> ClStack("asan-stack",
113 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
114 // This flag may need to be replaced with -f[no]asan-use-after-return.
115 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
116 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
117 // This flag may need to be replaced with -f[no]asan-globals.
118 static cl::opt<bool> ClGlobals("asan-globals",
119 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
120 static cl::opt<bool> ClInitializers("asan-initialization-order",
121 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
122 static cl::opt<bool> ClMemIntrin("asan-memintrin",
123 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
124 static cl::opt<bool> ClRealignStack("asan-realign-stack",
125 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
126 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
127 cl::desc("File containing the list of objects to ignore "
128 "during instrumentation"), cl::Hidden);
130 // These flags allow to change the shadow mapping.
131 // The shadow mapping looks like
132 // Shadow = (Mem >> scale) + (1 << offset_log)
133 static cl::opt<int> ClMappingScale("asan-mapping-scale",
134 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
135 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
136 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
137 static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
138 cl::desc("Use short immediate constant as the mapping offset for 64bit"),
139 cl::Hidden, cl::init(true));
141 // Optimization flags. Not user visible, used mostly for testing
142 // and benchmarking the tool.
143 static cl::opt<bool> ClOpt("asan-opt",
144 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
145 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
146 cl::desc("Instrument the same temp just once"), cl::Hidden,
148 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
149 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
151 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
152 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
153 cl::Hidden, cl::init(false));
156 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
158 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
159 cl::Hidden, cl::init(0));
160 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
161 cl::Hidden, cl::desc("Debug func"));
162 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
163 cl::Hidden, cl::init(-1));
164 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
165 cl::Hidden, cl::init(-1));
168 /// A set of dynamically initialized globals extracted from metadata.
169 class SetOfDynamicallyInitializedGlobals {
171 void Init(Module& M) {
172 // Clang generates metadata identifying all dynamically initialized globals.
173 NamedMDNode *DynamicGlobals =
174 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
177 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
178 MDNode *MDN = DynamicGlobals->getOperand(i);
179 assert(MDN->getNumOperands() == 1);
180 Value *VG = MDN->getOperand(0);
181 // The optimizer may optimize away a global entirely, in which case we
182 // cannot instrument access to it.
185 DynInitGlobals.insert(cast<GlobalVariable>(VG));
188 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
190 SmallSet<GlobalValue*, 32> DynInitGlobals;
193 /// This struct defines the shadow mapping using the rule:
194 /// shadow = (mem >> Scale) ADD-or-OR Offset.
195 struct ShadowMapping {
201 static ShadowMapping getShadowMapping(const Module &M, int LongSize,
202 bool ZeroBaseShadow) {
203 llvm::Triple TargetTriple(M.getTargetTriple());
204 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
205 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
206 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
207 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
209 ShadowMapping Mapping;
211 // OR-ing shadow offset if more efficient (at least on x86),
212 // but on ppc64 we have to use add since the shadow offset is not neccesary
213 // 1/8-th of the address space.
214 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
216 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
217 (LongSize == 32 ? kDefaultShadowOffset32 :
218 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
219 if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
220 assert(LongSize == 64);
221 Mapping.Offset = kDefaultShort64bitShadowOffset;
223 if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
224 // Zero offset log is the special case.
225 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
228 Mapping.Scale = kDefaultShadowScale;
229 if (ClMappingScale) {
230 Mapping.Scale = ClMappingScale;
236 static size_t RedzoneSizeForScale(int MappingScale) {
237 // Redzone used for stack and globals is at least 32 bytes.
238 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
239 return std::max(32U, 1U << MappingScale);
242 /// AddressSanitizer: instrument the code in module to find memory bugs.
243 struct AddressSanitizer : public FunctionPass {
244 AddressSanitizer(bool CheckInitOrder = false,
245 bool CheckUseAfterReturn = false,
246 bool CheckLifetime = false,
247 StringRef BlacklistFile = StringRef(),
248 bool ZeroBaseShadow = false)
250 CheckInitOrder(CheckInitOrder || ClInitializers),
251 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
252 CheckLifetime(CheckLifetime || ClCheckLifetime),
253 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
255 ZeroBaseShadow(ZeroBaseShadow) {}
256 virtual const char *getPassName() const {
257 return "AddressSanitizerFunctionPass";
259 void instrumentMop(Instruction *I);
260 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
261 Value *Addr, uint32_t TypeSize, bool IsWrite);
262 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
263 Value *ShadowValue, uint32_t TypeSize);
264 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
265 bool IsWrite, size_t AccessSizeIndex);
266 bool instrumentMemIntrinsic(MemIntrinsic *MI);
267 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
269 Instruction *InsertBefore, bool IsWrite);
270 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
271 bool runOnFunction(Function &F);
272 void createInitializerPoisonCalls(Module &M,
273 Value *FirstAddr, Value *LastAddr);
274 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
275 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
276 virtual bool doInitialization(Module &M);
277 static char ID; // Pass identification, replacement for typeid
280 void initializeCallbacks(Module &M);
282 bool ShouldInstrumentGlobal(GlobalVariable *G);
283 bool LooksLikeCodeInBug11395(Instruction *I);
284 void FindDynamicInitializers(Module &M);
287 bool CheckUseAfterReturn;
289 SmallString<64> BlacklistFile;
296 ShadowMapping Mapping;
297 Function *AsanCtorFunction;
298 Function *AsanInitFunction;
299 Function *AsanHandleNoReturnFunc;
300 OwningPtr<BlackList> BL;
301 // This array is indexed by AccessIsWrite and log2(AccessSize).
302 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
304 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
306 friend struct FunctionStackPoisoner;
309 class AddressSanitizerModule : public ModulePass {
311 AddressSanitizerModule(bool CheckInitOrder = false,
312 StringRef BlacklistFile = StringRef(),
313 bool ZeroBaseShadow = false)
315 CheckInitOrder(CheckInitOrder || ClInitializers),
316 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
318 ZeroBaseShadow(ZeroBaseShadow) {}
319 bool runOnModule(Module &M);
320 static char ID; // Pass identification, replacement for typeid
321 virtual const char *getPassName() const {
322 return "AddressSanitizerModule";
326 void initializeCallbacks(Module &M);
328 bool ShouldInstrumentGlobal(GlobalVariable *G);
329 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
331 size_t RedzoneSize() const {
332 return RedzoneSizeForScale(Mapping.Scale);
336 SmallString<64> BlacklistFile;
339 OwningPtr<BlackList> BL;
340 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
344 ShadowMapping Mapping;
345 Function *AsanPoisonGlobals;
346 Function *AsanUnpoisonGlobals;
347 Function *AsanRegisterGlobals;
348 Function *AsanUnregisterGlobals;
351 // Stack poisoning does not play well with exception handling.
352 // When an exception is thrown, we essentially bypass the code
353 // that unpoisones the stack. This is why the run-time library has
354 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
355 // stack in the interceptor. This however does not work inside the
356 // actual function which catches the exception. Most likely because the
357 // compiler hoists the load of the shadow value somewhere too high.
358 // This causes asan to report a non-existing bug on 453.povray.
359 // It sounds like an LLVM bug.
360 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
362 AddressSanitizer &ASan;
367 ShadowMapping Mapping;
369 SmallVector<AllocaInst*, 16> AllocaVec;
370 SmallVector<Instruction*, 8> RetVec;
371 uint64_t TotalStackSize;
372 unsigned StackAlignment;
374 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
375 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
377 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
378 struct AllocaPoisonCall {
379 IntrinsicInst *InsBefore;
383 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
385 // Maps Value to an AllocaInst from which the Value is originated.
386 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
387 AllocaForValueMapTy AllocaForValue;
389 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
390 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
391 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
392 Mapping(ASan.Mapping),
393 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
395 bool runOnFunction() {
396 if (!ClStack) return false;
397 // Collect alloca, ret, lifetime instructions etc.
398 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
399 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
400 BasicBlock *BB = *DI;
403 if (AllocaVec.empty()) return false;
405 initializeCallbacks(*F.getParent());
415 // Finds all static Alloca instructions and puts
416 // poisoned red zones around all of them.
417 // Then unpoison everything back before the function returns.
420 // ----------------------- Visitors.
421 /// \brief Collect all Ret instructions.
422 void visitReturnInst(ReturnInst &RI) {
423 RetVec.push_back(&RI);
426 /// \brief Collect Alloca instructions we want (and can) handle.
427 void visitAllocaInst(AllocaInst &AI) {
428 if (!isInterestingAlloca(AI)) return;
430 StackAlignment = std::max(StackAlignment, AI.getAlignment());
431 AllocaVec.push_back(&AI);
432 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
433 TotalStackSize += AlignedSize;
436 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
438 void visitIntrinsicInst(IntrinsicInst &II) {
439 if (!ASan.CheckLifetime) return;
440 Intrinsic::ID ID = II.getIntrinsicID();
441 if (ID != Intrinsic::lifetime_start &&
442 ID != Intrinsic::lifetime_end)
444 // Found lifetime intrinsic, add ASan instrumentation if necessary.
445 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
446 // If size argument is undefined, don't do anything.
447 if (Size->isMinusOne()) return;
448 // Check that size doesn't saturate uint64_t and can
449 // be stored in IntptrTy.
450 const uint64_t SizeValue = Size->getValue().getLimitedValue();
451 if (SizeValue == ~0ULL ||
452 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
454 // Find alloca instruction that corresponds to llvm.lifetime argument.
455 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
457 bool DoPoison = (ID == Intrinsic::lifetime_end);
458 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
459 AllocaPoisonCallVec.push_back(APC);
462 // ---------------------- Helpers.
463 void initializeCallbacks(Module &M);
465 // Check if we want (and can) handle this alloca.
466 bool isInterestingAlloca(AllocaInst &AI) {
467 return (!AI.isArrayAllocation() &&
468 AI.isStaticAlloca() &&
469 AI.getAllocatedType()->isSized());
472 size_t RedzoneSize() const {
473 return RedzoneSizeForScale(Mapping.Scale);
475 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
476 Type *Ty = AI->getAllocatedType();
477 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
480 uint64_t getAlignedSize(uint64_t SizeInBytes) {
481 size_t RZ = RedzoneSize();
482 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
484 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
485 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
486 return getAlignedSize(SizeInBytes);
488 /// Finds alloca where the value comes from.
489 AllocaInst *findAllocaForValue(Value *V);
490 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
491 Value *ShadowBase, bool DoPoison);
492 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
497 char AddressSanitizer::ID = 0;
498 INITIALIZE_PASS(AddressSanitizer, "asan",
499 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
501 FunctionPass *llvm::createAddressSanitizerFunctionPass(
502 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
503 StringRef BlacklistFile, bool ZeroBaseShadow) {
504 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
505 CheckLifetime, BlacklistFile, ZeroBaseShadow);
508 char AddressSanitizerModule::ID = 0;
509 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
510 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
511 "ModulePass", false, false)
512 ModulePass *llvm::createAddressSanitizerModulePass(
513 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
514 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
518 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
519 size_t Res = CountTrailingZeros_32(TypeSize / 8);
520 assert(Res < kNumberOfAccessSizes);
524 // Create a constant for Str so that we can pass it to the run-time lib.
525 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
526 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
527 return new GlobalVariable(M, StrConst->getType(), true,
528 GlobalValue::PrivateLinkage, StrConst,
532 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
533 return G->getName().find(kAsanGenPrefix) == 0;
536 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
538 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
539 if (Mapping.Offset == 0)
541 // (Shadow >> scale) | offset
542 if (Mapping.OrShadowOffset)
543 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
545 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
548 void AddressSanitizer::instrumentMemIntrinsicParam(
549 Instruction *OrigIns,
550 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
551 // Check the first byte.
553 IRBuilder<> IRB(InsertBefore);
554 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
556 // Check the last byte.
558 IRBuilder<> IRB(InsertBefore);
559 Value *SizeMinusOne = IRB.CreateSub(
560 Size, ConstantInt::get(Size->getType(), 1));
561 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
562 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
563 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
564 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
568 // Instrument memset/memmove/memcpy
569 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
570 Value *Dst = MI->getDest();
571 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
572 Value *Src = MemTran ? MemTran->getSource() : 0;
573 Value *Length = MI->getLength();
575 Constant *ConstLength = dyn_cast<Constant>(Length);
576 Instruction *InsertBefore = MI;
578 if (ConstLength->isNullValue()) return false;
580 // The size is not a constant so it could be zero -- check at run-time.
581 IRBuilder<> IRB(InsertBefore);
583 Value *Cmp = IRB.CreateICmpNE(Length,
584 Constant::getNullValue(Length->getType()));
585 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
588 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
590 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
594 // If I is an interesting memory access, return the PointerOperand
595 // and set IsWrite. Otherwise return NULL.
596 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
597 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
598 if (!ClInstrumentReads) return NULL;
600 return LI->getPointerOperand();
602 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
603 if (!ClInstrumentWrites) return NULL;
605 return SI->getPointerOperand();
607 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
608 if (!ClInstrumentAtomics) return NULL;
610 return RMW->getPointerOperand();
612 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
613 if (!ClInstrumentAtomics) return NULL;
615 return XCHG->getPointerOperand();
620 void AddressSanitizer::instrumentMop(Instruction *I) {
621 bool IsWrite = false;
622 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
624 if (ClOpt && ClOptGlobals) {
625 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
626 // If initialization order checking is disabled, a simple access to a
627 // dynamically initialized global is always valid.
630 // If a global variable does not have dynamic initialization we don't
631 // have to instrument it. However, if a global does not have initailizer
632 // at all, we assume it has dynamic initializer (in other TU).
633 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
638 Type *OrigPtrTy = Addr->getType();
639 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
641 assert(OrigTy->isSized());
642 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
644 if (TypeSize != 8 && TypeSize != 16 &&
645 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
646 // Ignore all unusual sizes.
651 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
654 // Validate the result of Module::getOrInsertFunction called for an interface
655 // function of AddressSanitizer. If the instrumented module defines a function
656 // with the same name, their prototypes must match, otherwise
657 // getOrInsertFunction returns a bitcast.
658 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
659 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
660 FuncOrBitcast->dump();
661 report_fatal_error("trying to redefine an AddressSanitizer "
662 "interface function");
665 Instruction *AddressSanitizer::generateCrashCode(
666 Instruction *InsertBefore, Value *Addr,
667 bool IsWrite, size_t AccessSizeIndex) {
668 IRBuilder<> IRB(InsertBefore);
669 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
671 // We don't do Call->setDoesNotReturn() because the BB already has
672 // UnreachableInst at the end.
673 // This EmptyAsm is required to avoid callback merge.
674 IRB.CreateCall(EmptyAsm);
678 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
681 size_t Granularity = 1 << Mapping.Scale;
682 // Addr & (Granularity - 1)
683 Value *LastAccessedByte = IRB.CreateAnd(
684 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
685 // (Addr & (Granularity - 1)) + size - 1
686 if (TypeSize / 8 > 1)
687 LastAccessedByte = IRB.CreateAdd(
688 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
689 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
690 LastAccessedByte = IRB.CreateIntCast(
691 LastAccessedByte, ShadowValue->getType(), false);
692 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
693 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
696 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
697 IRBuilder<> &IRB, Value *Addr,
698 uint32_t TypeSize, bool IsWrite) {
699 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
701 Type *ShadowTy = IntegerType::get(
702 *C, std::max(8U, TypeSize >> Mapping.Scale));
703 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
704 Value *ShadowPtr = memToShadow(AddrLong, IRB);
705 Value *CmpVal = Constant::getNullValue(ShadowTy);
706 Value *ShadowValue = IRB.CreateLoad(
707 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
709 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
710 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
711 size_t Granularity = 1 << Mapping.Scale;
712 TerminatorInst *CrashTerm = 0;
714 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
715 TerminatorInst *CheckTerm =
716 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
717 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
718 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
719 IRB.SetInsertPoint(CheckTerm);
720 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
721 BasicBlock *CrashBlock =
722 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
723 CrashTerm = new UnreachableInst(*C, CrashBlock);
724 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
725 ReplaceInstWithInst(CheckTerm, NewTerm);
727 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
731 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
732 Crash->setDebugLoc(OrigIns->getDebugLoc());
735 void AddressSanitizerModule::createInitializerPoisonCalls(
736 Module &M, Value *FirstAddr, Value *LastAddr) {
737 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
738 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
739 // If that function is not present, this TU contains no globals, or they have
740 // all been optimized away
744 // Set up the arguments to our poison/unpoison functions.
745 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
747 // Add a call to poison all external globals before the given function starts.
748 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
750 // Add calls to unpoison all globals before each return instruction.
751 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
753 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
754 CallInst::Create(AsanUnpoisonGlobals, "", RI);
759 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
760 Type *Ty = cast<PointerType>(G->getType())->getElementType();
761 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
763 if (BL->isIn(*G)) return false;
764 if (!Ty->isSized()) return false;
765 if (!G->hasInitializer()) return false;
766 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
767 // Touch only those globals that will not be defined in other modules.
768 // Don't handle ODR type linkages since other modules may be built w/o asan.
769 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
770 G->getLinkage() != GlobalVariable::PrivateLinkage &&
771 G->getLinkage() != GlobalVariable::InternalLinkage)
773 // Two problems with thread-locals:
774 // - The address of the main thread's copy can't be computed at link-time.
775 // - Need to poison all copies, not just the main thread's one.
776 if (G->isThreadLocal())
778 // For now, just ignore this Alloca if the alignment is large.
779 if (G->getAlignment() > RedzoneSize()) return false;
781 // Ignore all the globals with the names starting with "\01L_OBJC_".
782 // Many of those are put into the .cstring section. The linker compresses
783 // that section by removing the spare \0s after the string terminator, so
784 // our redzones get broken.
785 if ((G->getName().find("\01L_OBJC_") == 0) ||
786 (G->getName().find("\01l_OBJC_") == 0)) {
787 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
791 if (G->hasSection()) {
792 StringRef Section(G->getSection());
793 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
794 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
796 if ((Section.find("__OBJC,") == 0) ||
797 (Section.find("__DATA, __objc_") == 0)) {
798 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
801 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
802 // Constant CFString instances are compiled in the following way:
803 // -- the string buffer is emitted into
804 // __TEXT,__cstring,cstring_literals
805 // -- the constant NSConstantString structure referencing that buffer
806 // is placed into __DATA,__cfstring
807 // Therefore there's no point in placing redzones into __DATA,__cfstring.
808 // Moreover, it causes the linker to crash on OS X 10.7
809 if (Section.find("__DATA,__cfstring") == 0) {
810 DEBUG(dbgs() << "Ignoring CFString: " << *G);
818 void AddressSanitizerModule::initializeCallbacks(Module &M) {
820 // Declare our poisoning and unpoisoning functions.
821 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
822 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
823 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
824 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
825 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
826 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
827 // Declare functions that register/unregister globals.
828 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
829 kAsanRegisterGlobalsName, IRB.getVoidTy(),
830 IntptrTy, IntptrTy, NULL));
831 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
832 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
833 kAsanUnregisterGlobalsName,
834 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
835 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
838 // This function replaces all global variables with new variables that have
839 // trailing redzones. It also creates a function that poisons
840 // redzones and inserts this function into llvm.global_ctors.
841 bool AddressSanitizerModule::runOnModule(Module &M) {
842 if (!ClGlobals) return false;
843 TD = getAnalysisIfAvailable<DataLayout>();
846 BL.reset(new BlackList(BlacklistFile));
847 if (BL->isIn(M)) return false;
848 C = &(M.getContext());
849 int LongSize = TD->getPointerSizeInBits();
850 IntptrTy = Type::getIntNTy(*C, LongSize);
851 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
852 initializeCallbacks(M);
853 DynamicallyInitializedGlobals.Init(M);
855 SmallVector<GlobalVariable *, 16> GlobalsToChange;
857 for (Module::GlobalListType::iterator G = M.global_begin(),
858 E = M.global_end(); G != E; ++G) {
859 if (ShouldInstrumentGlobal(G))
860 GlobalsToChange.push_back(G);
863 size_t n = GlobalsToChange.size();
864 if (n == 0) return false;
866 // A global is described by a structure
869 // size_t size_with_redzone;
871 // size_t has_dynamic_init;
872 // We initialize an array of such structures and pass it to a run-time call.
873 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
876 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
879 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
881 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
883 // The addresses of the first and last dynamically initialized globals in
884 // this TU. Used in initialization order checking.
885 Value *FirstDynamic = 0, *LastDynamic = 0;
887 for (size_t i = 0; i < n; i++) {
888 static const uint64_t kMaxGlobalRedzone = 1 << 18;
889 GlobalVariable *G = GlobalsToChange[i];
890 PointerType *PtrTy = cast<PointerType>(G->getType());
891 Type *Ty = PtrTy->getElementType();
892 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
893 uint64_t MinRZ = RedzoneSize();
894 // MinRZ <= RZ <= kMaxGlobalRedzone
895 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
896 uint64_t RZ = std::max(MinRZ,
897 std::min(kMaxGlobalRedzone,
898 (SizeInBytes / MinRZ / 4) * MinRZ));
899 uint64_t RightRedzoneSize = RZ;
901 if (SizeInBytes % MinRZ)
902 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
903 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
904 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
905 // Determine whether this global should be poisoned in initialization.
906 bool GlobalHasDynamicInitializer =
907 DynamicallyInitializedGlobals.Contains(G);
908 // Don't check initialization order if this global is blacklisted.
909 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
911 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
912 Constant *NewInitializer = ConstantStruct::get(
913 NewTy, G->getInitializer(),
914 Constant::getNullValue(RightRedZoneTy), NULL);
916 SmallString<2048> DescriptionOfGlobal = G->getName();
917 DescriptionOfGlobal += " (";
918 DescriptionOfGlobal += M.getModuleIdentifier();
919 DescriptionOfGlobal += ")";
920 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
922 // Create a new global variable with enough space for a redzone.
923 GlobalVariable *NewGlobal = new GlobalVariable(
924 M, NewTy, G->isConstant(), G->getLinkage(),
925 NewInitializer, "", G, G->getThreadLocalMode());
926 NewGlobal->copyAttributesFrom(G);
927 NewGlobal->setAlignment(MinRZ);
930 Indices2[0] = IRB.getInt32(0);
931 Indices2[1] = IRB.getInt32(0);
933 G->replaceAllUsesWith(
934 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
935 NewGlobal->takeName(G);
936 G->eraseFromParent();
938 Initializers[i] = ConstantStruct::get(
940 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
941 ConstantInt::get(IntptrTy, SizeInBytes),
942 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
943 ConstantExpr::getPointerCast(Name, IntptrTy),
944 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
947 // Populate the first and last globals declared in this TU.
948 if (CheckInitOrder && GlobalHasDynamicInitializer) {
949 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
950 if (FirstDynamic == 0)
951 FirstDynamic = LastDynamic;
954 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
957 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
958 GlobalVariable *AllGlobals = new GlobalVariable(
959 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
960 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
962 // Create calls for poisoning before initializers run and unpoisoning after.
963 if (CheckInitOrder && FirstDynamic && LastDynamic)
964 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
965 IRB.CreateCall2(AsanRegisterGlobals,
966 IRB.CreatePointerCast(AllGlobals, IntptrTy),
967 ConstantInt::get(IntptrTy, n));
969 // We also need to unregister globals at the end, e.g. when a shared library
971 Function *AsanDtorFunction = Function::Create(
972 FunctionType::get(Type::getVoidTy(*C), false),
973 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
974 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
975 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
976 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
977 IRB.CreatePointerCast(AllGlobals, IntptrTy),
978 ConstantInt::get(IntptrTy, n));
979 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
985 void AddressSanitizer::initializeCallbacks(Module &M) {
987 // Create __asan_report* callbacks.
988 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
989 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
991 // IsWrite and TypeSize are encoded in the function name.
992 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
993 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
994 // If we are merging crash callbacks, they have two parameters.
995 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
996 checkInterfaceFunction(M.getOrInsertFunction(
997 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1001 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1002 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1003 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1004 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1005 StringRef(""), StringRef(""),
1006 /*hasSideEffects=*/true);
1009 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1010 // Tell the values of mapping offset and scale to the run-time.
1011 GlobalValue *asan_mapping_offset =
1012 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1013 ConstantInt::get(IntptrTy, Mapping.Offset),
1014 kAsanMappingOffsetName);
1015 // Read the global, otherwise it may be optimized away.
1016 IRB.CreateLoad(asan_mapping_offset, true);
1018 GlobalValue *asan_mapping_scale =
1019 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1020 ConstantInt::get(IntptrTy, Mapping.Scale),
1021 kAsanMappingScaleName);
1022 // Read the global, otherwise it may be optimized away.
1023 IRB.CreateLoad(asan_mapping_scale, true);
1027 bool AddressSanitizer::doInitialization(Module &M) {
1028 // Initialize the private fields. No one has accessed them before.
1029 TD = getAnalysisIfAvailable<DataLayout>();
1033 BL.reset(new BlackList(BlacklistFile));
1034 DynamicallyInitializedGlobals.Init(M);
1036 C = &(M.getContext());
1037 LongSize = TD->getPointerSizeInBits();
1038 IntptrTy = Type::getIntNTy(*C, LongSize);
1040 AsanCtorFunction = Function::Create(
1041 FunctionType::get(Type::getVoidTy(*C), false),
1042 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1043 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1044 // call __asan_init in the module ctor.
1045 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1046 AsanInitFunction = checkInterfaceFunction(
1047 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1048 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1049 IRB.CreateCall(AsanInitFunction);
1051 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1052 emitShadowMapping(M, IRB);
1054 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1058 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1059 // For each NSObject descendant having a +load method, this method is invoked
1060 // by the ObjC runtime before any of the static constructors is called.
1061 // Therefore we need to instrument such methods with a call to __asan_init
1062 // at the beginning in order to initialize our runtime before any access to
1063 // the shadow memory.
1064 // We cannot just ignore these methods, because they may call other
1065 // instrumented functions.
1066 if (F.getName().find(" load]") != std::string::npos) {
1067 IRBuilder<> IRB(F.begin()->begin());
1068 IRB.CreateCall(AsanInitFunction);
1074 bool AddressSanitizer::runOnFunction(Function &F) {
1075 if (BL->isIn(F)) return false;
1076 if (&F == AsanCtorFunction) return false;
1077 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1078 initializeCallbacks(*F.getParent());
1080 // If needed, insert __asan_init before checking for AddressSafety attr.
1081 maybeInsertAsanInitAtFunctionEntry(F);
1083 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1084 Attribute::AddressSafety))
1087 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1090 // We want to instrument every address only once per basic block (unless there
1091 // are calls between uses).
1092 SmallSet<Value*, 16> TempsToInstrument;
1093 SmallVector<Instruction*, 16> ToInstrument;
1094 SmallVector<Instruction*, 8> NoReturnCalls;
1097 // Fill the set of memory operations to instrument.
1098 for (Function::iterator FI = F.begin(), FE = F.end();
1100 TempsToInstrument.clear();
1101 int NumInsnsPerBB = 0;
1102 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1104 if (LooksLikeCodeInBug11395(BI)) return false;
1105 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1106 if (ClOpt && ClOptSameTemp) {
1107 if (!TempsToInstrument.insert(Addr))
1108 continue; // We've seen this temp in the current BB.
1110 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1113 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
1114 // A call inside BB.
1115 TempsToInstrument.clear();
1116 if (CI->doesNotReturn()) {
1117 NoReturnCalls.push_back(CI);
1122 ToInstrument.push_back(BI);
1124 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1130 int NumInstrumented = 0;
1131 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1132 Instruction *Inst = ToInstrument[i];
1133 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1134 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1135 if (isInterestingMemoryAccess(Inst, &IsWrite))
1136 instrumentMop(Inst);
1138 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1143 FunctionStackPoisoner FSP(F, *this);
1144 bool ChangedStack = FSP.runOnFunction();
1146 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1147 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1148 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1149 Instruction *CI = NoReturnCalls[i];
1150 IRBuilder<> IRB(CI);
1151 IRB.CreateCall(AsanHandleNoReturnFunc);
1153 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1155 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1158 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1159 if (ShadowRedzoneSize == 1) return PoisonByte;
1160 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1161 if (ShadowRedzoneSize == 4)
1162 return (PoisonByte << 24) + (PoisonByte << 16) +
1163 (PoisonByte << 8) + (PoisonByte);
1164 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1167 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1170 size_t ShadowGranularity,
1172 for (size_t i = 0; i < RZSize;
1173 i+= ShadowGranularity, Shadow++) {
1174 if (i + ShadowGranularity <= Size) {
1175 *Shadow = 0; // fully addressable
1176 } else if (i >= Size) {
1177 *Shadow = Magic; // unaddressable
1179 *Shadow = Size - i; // first Size-i bytes are addressable
1184 // Workaround for bug 11395: we don't want to instrument stack in functions
1185 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1186 // FIXME: remove once the bug 11395 is fixed.
1187 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1188 if (LongSize != 32) return false;
1189 CallInst *CI = dyn_cast<CallInst>(I);
1190 if (!CI || !CI->isInlineAsm()) return false;
1191 if (CI->getNumArgOperands() <= 5) return false;
1192 // We have inline assembly with quite a few arguments.
1196 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1197 IRBuilder<> IRB(*C);
1198 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1199 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1200 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1201 kAsanStackFreeName, IRB.getVoidTy(),
1202 IntptrTy, IntptrTy, IntptrTy, NULL));
1203 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1204 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1205 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1206 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1209 void FunctionStackPoisoner::poisonRedZones(
1210 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1212 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1213 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1214 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1215 Type *RZPtrTy = PointerType::get(RZTy, 0);
1217 Value *PoisonLeft = ConstantInt::get(RZTy,
1218 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1219 Value *PoisonMid = ConstantInt::get(RZTy,
1220 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1221 Value *PoisonRight = ConstantInt::get(RZTy,
1222 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1224 // poison the first red zone.
1225 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1227 // poison all other red zones.
1228 uint64_t Pos = RedzoneSize();
1229 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1230 AllocaInst *AI = AllocaVec[i];
1231 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1232 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1233 assert(AlignedSize - SizeInBytes < RedzoneSize());
1238 assert(ShadowBase->getType() == IntptrTy);
1239 if (SizeInBytes < AlignedSize) {
1240 // Poison the partial redzone at right
1241 Ptr = IRB.CreateAdd(
1242 ShadowBase, ConstantInt::get(IntptrTy,
1243 (Pos >> Mapping.Scale) - ShadowRZSize));
1244 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1245 uint32_t Poison = 0;
1247 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1249 1ULL << Mapping.Scale,
1250 kAsanStackPartialRedzoneMagic);
1252 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1253 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1256 // Poison the full redzone at right.
1257 Ptr = IRB.CreateAdd(ShadowBase,
1258 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1259 bool LastAlloca = (i == AllocaVec.size() - 1);
1260 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1261 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1263 Pos += RedzoneSize();
1267 void FunctionStackPoisoner::poisonStack() {
1268 uint64_t LocalStackSize = TotalStackSize +
1269 (AllocaVec.size() + 1) * RedzoneSize();
1271 bool DoStackMalloc = ASan.CheckUseAfterReturn
1272 && LocalStackSize <= kMaxStackMallocSize;
1274 assert(AllocaVec.size() > 0);
1275 Instruction *InsBefore = AllocaVec[0];
1276 IRBuilder<> IRB(InsBefore);
1279 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1280 AllocaInst *MyAlloca =
1281 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1282 if (ClRealignStack && StackAlignment < RedzoneSize())
1283 StackAlignment = RedzoneSize();
1284 MyAlloca->setAlignment(StackAlignment);
1285 assert(MyAlloca->isStaticAlloca());
1286 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1287 Value *LocalStackBase = OrigStackBase;
1289 if (DoStackMalloc) {
1290 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1291 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1294 // This string will be parsed by the run-time (DescribeStackAddress).
1295 SmallString<2048> StackDescriptionStorage;
1296 raw_svector_ostream StackDescription(StackDescriptionStorage);
1297 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1299 // Insert poison calls for lifetime intrinsics for alloca.
1300 bool HavePoisonedAllocas = false;
1301 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1302 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1303 IntrinsicInst *II = APC.InsBefore;
1304 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1306 IRBuilder<> IRB(II);
1307 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1308 HavePoisonedAllocas |= APC.DoPoison;
1311 uint64_t Pos = RedzoneSize();
1312 // Replace Alloca instructions with base+offset.
1313 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1314 AllocaInst *AI = AllocaVec[i];
1315 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1316 StringRef Name = AI->getName();
1317 StackDescription << Pos << " " << SizeInBytes << " "
1318 << Name.size() << " " << Name << " ";
1319 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1320 assert((AlignedSize % RedzoneSize()) == 0);
1321 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1322 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1324 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1325 AI->replaceAllUsesWith(NewAllocaPtr);
1326 Pos += AlignedSize + RedzoneSize();
1328 assert(Pos == LocalStackSize);
1330 // Write the Magic value and the frame description constant to the redzone.
1331 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1332 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1334 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1335 ConstantInt::get(IntptrTy,
1337 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1338 GlobalVariable *StackDescriptionGlobal =
1339 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1340 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1342 IRB.CreateStore(Description, BasePlus1);
1344 // Poison the stack redzones at the entry.
1345 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1346 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1348 // Unpoison the stack before all ret instructions.
1349 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1350 Instruction *Ret = RetVec[i];
1351 IRBuilder<> IRBRet(Ret);
1352 // Mark the current frame as retired.
1353 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1355 // Unpoison the stack.
1356 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1357 if (DoStackMalloc) {
1358 // In use-after-return mode, mark the whole stack frame unaddressable.
1359 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1360 ConstantInt::get(IntptrTy, LocalStackSize),
1362 } else if (HavePoisonedAllocas) {
1363 // If we poisoned some allocas in llvm.lifetime analysis,
1364 // unpoison whole stack frame now.
1365 assert(LocalStackBase == OrigStackBase);
1366 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1370 // We are done. Remove the old unused alloca instructions.
1371 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1372 AllocaVec[i]->eraseFromParent();
1375 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1376 IRBuilder<> IRB, bool DoPoison) {
1377 // For now just insert the call to ASan runtime.
1378 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1379 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1380 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1381 : AsanUnpoisonStackMemoryFunc,
1385 // Handling llvm.lifetime intrinsics for a given %alloca:
1386 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1387 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1388 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1389 // could be poisoned by previous llvm.lifetime.end instruction, as the
1390 // variable may go in and out of scope several times, e.g. in loops).
1391 // (3) if we poisoned at least one %alloca in a function,
1392 // unpoison the whole stack frame at function exit.
1394 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1395 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1396 // We're intested only in allocas we can handle.
1397 return isInterestingAlloca(*AI) ? AI : 0;
1398 // See if we've already calculated (or started to calculate) alloca for a
1400 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1401 if (I != AllocaForValue.end())
1403 // Store 0 while we're calculating alloca for value V to avoid
1404 // infinite recursion if the value references itself.
1405 AllocaForValue[V] = 0;
1406 AllocaInst *Res = 0;
1407 if (CastInst *CI = dyn_cast<CastInst>(V))
1408 Res = findAllocaForValue(CI->getOperand(0));
1409 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1410 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1411 Value *IncValue = PN->getIncomingValue(i);
1412 // Allow self-referencing phi-nodes.
1413 if (IncValue == PN) continue;
1414 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1415 // AI for incoming values should exist and should all be equal.
1416 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1422 AllocaForValue[V] = Res;